Thursday, March 19, 2015
Exhibit Hall Poster Area 1 (Convention Center)
Background/Purpose: Explosive, strong, and stable movements from the legs are crucial to the performance of volleyball players, as they must execute many dynamic movements on the court. However, a large quadriceps angle (Q-angle), common in females, can hinder the patellar tracking between the femoral condyles during knee flexion and extension. Q-angles exceeding 15-20 degrees have an inverse relationship with quadriceps strength (Byl, 2010). Quadriceps strength (QS) is optimal at Q-angles of less than 10 degrees, which allows for the most efficient line of pull of the quadriceps muscle (Byl, 2000). Excessive Q-angles have shown decreased knee strength due to additional work created by the body to control motion (Claiborne, 2006). This creates a compensatory mechanism where humans must use some of the total muscular energy for stability and control of the knee instead of putting maximal effort into strength of contraction. The purpose of this study was to determine the relationship between QS and Q-angle. It was hypothesized that an excessive Q-angle decreases QS in collegiate female volleyball players. Method: The experimental design was carried out by recruiting ten females (age = 19.3 ± 1.337 yrs.; ht. = 175.66 ± 5.59 cm; wt. = 67.52 ± 9.67 kg; yrs. exp. = 8.9 ± 2.558 yrs.) from a NCAA Division III Midwest varsity volleyball team. Each participant completed a manual muscle test (MMT) of the quadriceps, one repetition maximum (1RM) leg press to determine relative leg strength (RLS), and Q-angle measurement on right (Rt) and left (Lt) legs. Data was analyzed using the Pearson Product Moment correlation in Minitab 16. Analysis/Results: Data analysis revealed an extremely low relationship between Q-angle (Rt = 20.60 ± 3.92; Lt= 21.20 ± 6.06) and QS (Rt=24.90 ± 5.47; Lt= 25.22 ± 7.02) in the MMT (R=0.16; p=0.49) as well as between dominant leg Q-angle (20.60 ± 3.92) and RLS (2.93 ± 0.47) from the 1RM (R=-0.037; p=0.92). Conclusions: There was no significant relationship between excessive Q-angle and its effect on maximal QS. These results would be important to individuals interested in how q-angle effects the body’s biomechanics, particularly regarding gender differences and athletics.